Endocrine Principles

Question 1

examples of peptide hormones

Answer 1

oxytocin
GH
FSH

Question 2

what amino acid is adrenaline derived from

Answer 2

tyrosine

Question 3

what amino acid is melatonin derived from

Answer 3

tryptophan

Question 4

describe the action ofd tyrosine kinase receptors and what hormone receptor is TK

Answer 4

extracellular region that acts with ligand, translated to tyrosine kinase domain intracellularly
Insulin

Question 5

describe the action of GPCR, their transmembrane domain

Answer 5

7 fold transmembrane domain
ligand binds to extracellular domain to evoke intracellular response by intracellular domain activating alpha/beta/gamma subunits to mediate effect

Question 6

what hormones utilise steroid hormone receptors and how do they work

Answer 6

intracellular in cytoplasm or nucleus and bind to DNA response elements to evoke change in gene transcription
oestrogen, testosterone, glucocorticoid

Question 7

describe the hypothalamic-pituitary axis

Answer 7

specialised neurons in hypothalamus release specific hormones to act on pituitary gland to release endocrine glands
controlled by -ve feedback

Question 8

factors affecting clinical hormone measurement

Answer 8

pattern of secretion 
carrier protein presence 
interfering agents 
hormone stability and 1/2 life 
absolute concn

Question 9

true/false - thyroid function should be measured in acute illness

Answer 9

false - it forms little value unless considered central to clinical practice, ie thyroid storm

Question 10

describe the thyroid axis

Answer 10

hypothalamus releases TRH to anterior pituitary to release TSH
TSH stimulated thyroid to release FT4, FT3, liothyronine
FT4 and FT3 have negative feedback on pituitary and hypothalamus to keep concn in a narrow window

Question 11

raised TSH with low FT4 and FT3 is indicative of?

Answer 11

hypothyroidism

Question 12

low TSH with high FT4 and FT3 is indicative of?

Answer 12

hyperthyroidism

Question 13

when is TSH not a reliable marker of thyroid function

Answer 13

anterior pituitary dysfunction

Question 14

describe the hypothalmic-pituitary-adrenal axis

Answer 14

hypothalamus secretes CRH to ant pituitary to release ACTH on adrenal cortex tp secrete cortisol
-ve feedback on ant pituitary and hypothalamus

Question 15

what rhythm does cortisol production have and rescribe it

Answer 15

circadian
rise in morning and slowly drops over day until nearly zero at night
rises again in anticipation for day ahead

Question 16

describe the hypothalamic-pituitary gonadal axis

Answer 16

hypothalamis neurons stimulated to cause GnRH secretion to act on ant pituitary to release FSH/LH
these can also act on endocrine cells to secrete steroid/peptide hormones
-ve feedback

Question 17

rhythm of testosterone

Answer 17

highest in morning, dips and begins to rise again early evening and overnight
circadian

Question 18

describe prolactin secretion

Answer 18

secreted by ant pituitary but under inhibitory control by tonic dopamine
after secretion excess prolactin -ve feedback to hypothalamus to increase dopamine secretion again

Question 19

dynaic testing - a suppression test is used for

Answer 19

hormone excess

Question 20

dynamic testing - a stimulation test is used for

Answer 20

hormone deficiency

Question 21

what is primary adrenal failure also known as

Answer 21

addisons disease

Question 22

what is an excess of cortisol known as and what are possible causes

Answer 22

cushings syndrome
exogenous steroids
pituitary/adrenal origin
ectopic ACTH

Question 23

stimulation test for addisons?

Answer 23

synacthen test

Question 24

stimulation test for cushings and how does ACTH help

Answer 24

dexamethasone suppression test
failure to suppress is cushings
measure of high ACTH determines whether its cushings or ectopic ACTH
measure of low ACTH implies adrenal origin

Question 25

features of cushings syndrome

Answer 25

``` cushingoid appearance hirtuism acne abdominal striae interscapular fat pad proximal myopathy osteoporosis hypertension impaired glucose tolerance ```

Question 26

autocrine regulation

Answer 26

chemicals released from cells bind to receptors on the cells that are releasing them

Question 27

paracrine regulation

Answer 27

cell modulates an adjacent cell

Question 28

endocrine regulation

Answer 28

chemicals released from secretory cells into circulatory cells to reach target tissue and evoke response

Question 29

what are hormones

Answer 29

substance elaborated by one cell to regulate another by autocrine, paracrine or endocrine route

Question 30

what does the hypothalamus do

Answer 30

controls activity of secretion of ant pituitary controls post pituitary by neural control synthesises post pituitary hormones neural control over adrenal medulla

Question 31

how do steroid hormones travel in blood

Answer 31

travel either free or bound to carrier proteins

Question 32

mechanism of action of steroid hormones

Answer 32

diffuse through cell membrane bind to hormone receptor to form a complex within the cell binds to DNA to activate specific genes leads to production of key substances

Question 33

true/false - amine derived hormones such as catecholamines or thyroid hormones cannot be stored in their synthesising organ

Answer 33

false - they can

Question 34

describe insulin secretion from elevated blood glucose

Answer 34

increased blood glucose travels into B cell by GLUT2 converted to G-6-P by glucokinase and metabolised in the metabolism ATP acts to close ATP K channel and cause membrane depolarisation opening of Ca channels increases intracellular Ca and so triggers secretion of insulin

Question 35

what effects do carrier proteins have on hormone transport

Answer 35

facilitates transport increases half life reservoir for hormone

Question 36

how can those with leptin deficiency/defective receptors develop diabetes?

Answer 36

leptin in high quantities can suppress appetite and increase thermogenesis so in lack of receptor or leptin this can cause unrestrained appetite

Question 37

mechanism of action of orlistat

Answer 37

lipase inhibitor so blocks up to 1/3 ingested fat being absorbed

Question 38

3 types of bariatric surgery?

Answer 38

gastric bypass sleeve gastrectomy roux-en-Y gastric bypass

Question 39

why is is harder to lose weight at a lower weight

Answer 39

adaptive thermogenesis -resting metabolic rate is higher in obese and falls in weight loss lower the BMR the harder it is to lose this weight and keep it off

Question 40

what do alpha cells secrete

Answer 40

glucagon

Question 41

what do beta cells secrete

Answer 41

insulin

Question 42

waht do delta cells secrete

Answer 42

somatostatin

Question 43

what do PP cells secrete

Answer 43

pancreatic polypeptide

Question 44

what do epsilon cells secrete

Answer 44

ghrelin

Question 45

true/false - in T2DM glucagon secretion is suppressed

Answer 45

false - due to insulin resistance glucagon may remain active and so can lead to further hyperglycaemia

Question 46

what is the incretin effect

Answer 46

oral glucose administration induces greater insulin secretion than IV administration of an isoglycaemic dose of insulin this is because GLP-1 is produced to stimulate beta cells further

Question 47

what breaks down GLP-1

Answer 47

DPPIV